cat /etc/postfix/mysql-email.cf
user = mailadmin
password = xxx
dbname = mail
query = SELECT email FROM users WHERE email='%s'
hosts = 127.0.0.1

cat /etc/postfix/mysql-forwards.cf
user = mailadmin
password = xxx
dbname = mail
query = SELECT destination FROM forwards WHERE source='%s'
hosts = 127.0.0.1

at /etc/postfix/mysql-domains.cf
user = mailadmin
password = xxx
dbname = mail
query = SELECT domain AS virtual FROM domains WHERE domain='%s'
hosts = 127.0.0.1

cat /etc/postfix/mysql-mailboxes.cf
user = mailadmin
password = xxx
dbname = mail
query = SELECT CONCAT(SUBSTRING_INDEX(email,'@',-1),'/',SUBSTRING_INDEX(email,'@',1),'/') FROM users WHERE email='%s'
hosts = 127.0.0.1

cat /etc/postfix/sasl/smtpd.conf
pwcheck_method: auxprop
    auxprop_plugin: sql
    mech_list: PLAIN LOGIN CRAM-MD5 DIGEST-MD5 NTLM
sql_engine: mysql
sql_hostnames: 127.0.0.1
sql_user: mailadmin
sql_passwd: xxx
sql_database: mail
sql_select: select password from users where email = '%u'